Method of distinguishing hybrid automatic repeat request processes and related communication device

ABSTRACT

A method of distinguishing hybrid automatic repeat request, hereinafter called HARQ, processes for a mobile device of a wireless communication system includes assigning a plurality of HARQ reference numbers corresponding to a plurality of uplink HARQ processes respectively, for identifying each of the plurality of uplink HARQ processes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/141,247, filed on Dec. 30, 2008 and entitled “Method for HandlingData Transmission with TTI bundling in Wireless Communication System andRelated Communication Device” the contents of which are incorporatedherein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

A method utilized in a wireless communication and communication devicethereof is disclosed, and more particularly, to a method fordistinguishing hybrid automatic repeat request processes in a wirelesscommunication system and communication device thereof.

2. Description of the Prior Art

A long-term evolution (LTE) system, initiated by the third generationpartnership project (3GPP), is now being regarded as a new radiointerface and radio network architecture that provides a high data rate,low latency, packet optimization, and improved system capacity andcoverage. In the LTE system, an evolved universal terrestrial radioaccess network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs)and communicates with a plurality of mobile stations, also referred asuser equipments (UEs).

Architecture of the radio interface protocol of the LTE system includesthree layers: the Physical Layer (L1), the Data Link Layer (L2), and theNetwork Layer (L3), wherein a control plane of L3 is a Radio ResourceControl (RRC) layer, and L2 is further divided into a Packet DataConvergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer anda Medium Access Control (MAC) layer.

In the LTE system, the main services and functions of the MAC layerinclude error correction through Hybrid Automatic Repeat Request (HARQ),and Transmission Time Interval (TTI) bundling transmission.

For uplink scheduling with HARQ, if the PDCCH (Physical Downlink ControlChannel) indicates the UE to receive a packet, but the packet cannot bedecoded successfully on an Uplink Share Channel (UL-SCH), the MAC layerof the UE performs an uplink HARQ process to request a retransmission ofthe packet. Since the UE would not receive any retransmission packetduring a signaling round trip time (RTT) of the HARQ process, a HARQ RTTTimer is thus configured. Note that, the uplink HARQ process isassociated with HARQ information consisting of a New Data Indicator(NDI), a Redundancy Version (RV) and a Transport Block (TB) size.

In addition, there is one HARQ entity at the MAC layer, which maintainsa number of parallel uplink HARQ processes allowing transmissions totake place continuously while waiting for the feedback on the successfulor unsuccessful reception of previous transmissions. An operation of theHARQ entity for each TTI includes identifying the HARQ processassociated with the TTI, if an uplink grant has been indicated for theTTI, delivering the uplink grant including HARQ information receivedfrom the eNBs to the identified HARQ process, and finally instructingthe identified HARQ process to generate a new transmission or aretransmission.

Moreover, a TTI bundling operation (or so-called subframe bundlingoperation) is introduced to improve LTE uplink coverage without theoverhead associated with L2 segmentation and the issues with ACK(Acknowledgement)/NAK (Negative Acknowledgement) errors. The UEactivating the TTI bundling is allowed to transmit the same packet inconsecutive TTIs/subframes. The UE in cell boundary utilizing TTIbundling transmission can reduce transmission delay. The activation anddeactivation of TTI bundling transmission is done by RRC signalingmessage.

If TTI bundling is configured by RRC, the parameter TTI_BUNDLE_SIZEprovides the number of subframes of a subframe bundle. Within a bundleHARQ retransmissions are non-adaptive and are performed without waitingfor feedbacks (e.g. NACK or ACK) from previous transmissions accordingto TTI_BUNDLE_SIZE. A feedback for a bundle is only received for aspecific TTI corresponding to TTI_BUNDLE_SIZE. A retransmission of a TTIbundle is also a TTI bundle.

Furthermore, for transmission of an uplink message containing a C-RNTI(Cell Radio Network Temporary Identifier) MAC control element or anuplink message including a CCCH (Common Control Channel) SDU (ServiceData Unit) during a random access procedure, the TTI bundling does notapply.

The prior art does not appear to specify how to identify the uplink HARQprocess associated with the subframe bundling operation. Moreover, theHARQ entity maintains at most 8 parallel HARQ processes in the uplinkfor non-subframe bundling operation, and at most 4 HARQ processes in theuplink for subframe bundling operation. This means that the number ofthe HARQ processes changes when the UE activate or deactivate thesubframe bundling operation. However, when a transit between thenon-subframe and subframe bundling operations occurs, the UE does notknow which HARQ processes are kept activated and also does not knowwhich HARQ process corresponds to which set of HARQ information receivedafter the transit. Applying the wrong HARQ information to a HARQ processcauses data transmission errors. The UE can encounter a number of issuesas described below.

Issue 1: Consider the UE has 8 HARQ processes being used for uplinktransmission in the non-subframe bundling operation. Since the prior artdoes not clearly specify how to identify a HARQ process associated withthe subframe, the UE has a difficulty in distinguishing the HARQ processassociated with the subframe without any means of identifying the HARQprocess, and thereby is liable to use the HARQ information received fromthe eNBs for the wrong HARQ process. For example, when the UE receivesan uplink grant with an NDI, the UE cannot distinguish which of the 8HARQ processes the NDI is for. Since the UE cannot determine the NDI ifis toggled or not, the UE may generate a transmission for an expectedretransmission or a retransmission for an expected transmission.

Issue 2: When the subframe bundling operation is configured, 4 of 8 HARQprocesses are used for uplink transmission and the other 4 processes aresuspended according to the prior art. However, the prior art does notappear to specify which 4 processes are used for uplink transmission.Without specification, as mentioned above, the UE cannot know if the NDIis toggled and then cannot decide to transmit a new transmission orperform an adaptive retransmission.

Take an issue 3 for example. When the subframe bundle is de-configured,the prior art does not appear to specify how to resume uplinktransmission for a suspended HARQ process. Without specifying which ofthe 8 processes is resumed first, as in issue 1, when the UE receives anuplink grant with the NDI, the UE cannot determine which process the NDIis for. Therefore, it is not known if the first transmission of thesuspended process is a new transmission or a retransmission.

In addition to the issues mentioned above, a Message 3 transmissioninapplicable for the subframe bundling operation can cause transmissionerrors when the subframe bundling operation is in-use. The Message 3transmission is transmission of a random access procedure and can beperformed with a HARQ process. The interval between retransmissions anda new transmission of the HARQ process is 8 ms (HARQ RTT) in thenon-subframe bundling operation, but 16 ms in the subframe bundlingoperation. During the subframe bundling operation, the Message 3transmission of the random access procedure does not apply bundlingtransmission according to the prior art, but still applies 16 ms HARQRTT of the bundling transmission to the HARQ process, which delays therandom access procedure completion since the Message 3 retransmissiontiming in the HARQ process is doubled.

Furthermore, as mentioned above, in a subframe bundling operation, theMessage 3 transmission and retransmissions do not apply bundlingtransmission. However, if the Message 3 transmission collides with asubframe bundle transmission, the prior art does not appear to specifyhow to deal with this case.

SUMMARY OF THE INVENTION

A method for distinguishing uplink hybrid automatic repeat request(HARQ) processes is disclosed in a wireless communication system andrelated communication device to solve the abovementioned problems.

A method of distinguishing HARQ processes is disclosed for a mobiledevice of a wireless communication system. The method comprisesassigning a plurality of HARQ reference numbers corresponding to aplurality of uplink HARQ processes respectively, for identifying each ofthe plurality of uplink HARQ processes.

A method of distinguishing HARQ processes is disclosed for a mobiledevice of a wireless communication system. The method comprisesreplacing a single subframe of the subframe bundle transmission with atransmission of the Message 3 when the transmission of the Message 3collides with the subframe bundle transmission at the subframe.

These and other objectives will no doubt become obvious to those ofordinary skill in the art after reading the following detaileddescription of the preferred embodiment that is illustrated in thevarious figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary wireless communicationsystem.

FIG. 2 is a schematic diagram of an exemplary communication deviceaccording to an embodiment.

FIG. 3 is a schematic diagram of exemplary program code for the LTEsystem according to an embodiment.

FIG. 4 is a flowchart of an exemplary process according to a firstembodiment.

FIG. 5 is a schematic diagram of exemplary HARQ reference numbersassociated to subframes according to an embodiment.

FIG. 6 is a flowchart of an exemplary process according to a secondembodiment.

FIGS. 7 and 8 are schematic diagrams of exemplary HARQ reference numbersassociated to subframes according to an embodiment.

FIG. 9 is a flowchart of an exemplary process according to a thirdembodiment.

FIG. 10 illustrates a flowchart of an exemplary process according to afourth embodiment.

FIG. 11 illustrates a flowchart of an exemplary process according to afifth embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates a schematic diagram of a wireless communicationsystem 50 according to an embodiment. Briefly, the wirelesscommunication system 50 is composed of a network and a plurality ofmobile devices. The wireless communication system 50 can be a UMTS(Universal Mobile Telecommunications System) or an LTE (long-termevolution) system or any other similar network system. In the LTEsystem, the network is referred as a EUTRAN (evolved-UTRAN) comprising aplurality of eNBs, whereas the mobile devices are referred as userequipments (UEs). The UEs can be devices such as mobile phones, computersystems, etc. This terminology will be used throughout the applicationfor ease of reference, and however, this should not be construed aslimiting the invention to any one particular type of network. Thenetwork and the UE can be seen as a transmitter or receiver according totransmission direction, e.g., for uplink (UL), the UE is the transmitterand the network is the receiver, and for downlink (DL), the network isthe transmitter and the UE is the receiver.

FIG. 2 illustrates a schematic diagram of a communication device 60according to an embodiment of the present invention. The communicationdevice 60 can be the mobile devices shown in FIG. 1 and may include aprocessor means 600 such as a microprocessor or ASIC, a memory unit 610and a communication interfacing unit 620. The memory unit 610 may be anydata storage device that can store program code 614, for access by theprocessing means 600. Examples of the memory unit 610 include but arenot limited to a subscriber identity module (SIM), read-only memory(ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, hard disks,and optical data storage devices. The communication interfacing unit 620is preferably a radio transceiver and can exchange wireless signals withthe network according to processing results of the processing means 600.

FIG. 3 illustrates a schematic diagram of the program code 614 for theLTE system according to an embodiment. The program code 614 includesprogram code of multiple communications protocol layers, which from topto bottom are a radio resource control (RRC) layer 700, a packet dataconvergence protocol (PDCP) layer 710, a radio link control (RLC) layer720, a medium access control (MAC) layer 730 and a physical (PHY) layer740. In any given layer, a service data unit (SDU) is a packet receivedfrom an upper layer, and a protocol data unit (PDU) is a packet thatincludes a header of that layer and zero or more SDUs and is transmittedto a lower layer.

The RRC layer 710 is used for configuring an activation state of a TTI(Transmission Time Interval) bundling operation (also referred to as asubframe bundling operation) and using a TTI_BUNDLE_SIZE parameter toset a size of a TTI/subframe bundle. The MAC layer 730 is responsiblefor handling the TTI bundling operation, such as handling activation anddeactivation of the TTI bundling operation and handling applicabletargets, by itself or based on RRC configuration. In addition, the MAClayer 730 performs HARQ (Hybrid Automatic Repeat Request) processes formultiple transmissions of transport blocks and a random access procedureincluding transmission of a random access preamble, reception of arandom access response, and transmission of a Message 3 MAC PDU. The PHYlayer 740 is capable of monitoring a physical downlink control channelfor receiving an uplink grant, HARQ information, etc from eNBs. With theuplink grant, the MAC layer 730 is allowed to perform data transmissionof a specific HARQ process at a specific TTI based on the HARQinformation. With the TTI bundling operation, the communication device60 is able to transmit the same packet (e.g. PDU) or transport block inconsecutive TTIs/subframes.

The flowchart of FIG. 4 illustrates a process 80 according to anembodiment. The process 80 is utilized for distinguishing a plurality ofuplink HARQ processes in a non-subframe bundling operation for a UE of awireless communication system. The process 80 can be compiled into theprogram code 614 and includes the following steps:

Step 800: Start.

Step 802: Assign a plurality of HARQ reference numbers corresponding toa plurality of uplink HARQ processes respectively, for identifying eachof the plurality of uplink HARQ processes.

Step 804: End.

According to the process 80, each of the plurality of uplink HARQprocesses is assigned a HARQ reference number for identifying each ofthe uplink HARQ processes. With the HARQ reference number assignment,the UE is able to distinguish which uplink HARQ process a receivedpacket or a packet for transmission belongs to. In addition, the process80 is applied to an eNB of the wireless communication system. That is,the eNB also assigns a HARQ reference number to HARQ informationcorresponding to each of the uplink HARQ processes when allocatingcorresponding uplink grant to the UE. Therefore, the UE can distinguishthe HARQ information received from the eNB is for which HARQ process ofthe plurality of the HARQ processes, so as to generate an expectedtransmission, such as a new transmission or an adaptive/non-adaptiveretransmission.

In addition, when the UE receives an uplink grant from the eNB, the UEcan correctly determine a New Data Indicator (NDI) toggle state for aHARQ process according to a NDI value in the stored HARQ information andanother NDI value in the received uplink grant, and thereby generate anew transmission or an adaptive retransmission for an expectedtransmission according to the NDI toggle state. When the NDI is toggled,which indicates the NDI value in the stored HARQ information isdifferent with the NDI value in the uplink grant, the new transmissionis generated thereof, and when the NDI is not toggled, which indicatesthe NDI value in the stored HARQ information is the same with the NDIvalue in the uplink grant, the adaptive retransmission is generatedthereof.

Each HARQ reference number can be generated according to a HARQ roundtrip time (RTT) controlled by a HARQ RTT Timer and a subframe number ofcorresponding subframe by the following equation (E1):m=(subframe counter)mod(HARQ round trip time),

where m is the HARQ reference number, the subframe counter is an integerand is incremented by one every subframe with a predetermined cycle andmod is a modulus operation.

Preferably, the subframe counter is (10*SFN+subframe number+k), whereinSFN indicates a system frame number, and k is 0 or an integer. In thissituation, the HARQ reference number m is obtained by the followingequation (E2):m=(10*SFN+subframe number+k)mod(HARQ round trip time).

FIG. 5 illustrates HARQ reference numbers of corresponding HARQprocesses associated to subframes based on the abovementioned example.The UE operates through SFNs (System Frame Numbers) ‘0’-‘2’, and eachsystem frame consists of subframes with subframe numbers ‘0’-‘9’. A HARQRTT timer is set to 8 subframes (8 milliseconds), and 8 HARQ processesare activated for uplink. According to the abovementioned equation (E2),HARQ reference numbers (HRN) of the HARQ processes associated withsubframes are determined to be a cyclic sequence from 0 to 7.

By assigning the HARQ reference numbers to the HARQ processes and HARQinformation, when the UE receives an uplink grant along with the HARQinformation, the UE can distinguish which uplink HARQ process the HARQinformation received from the eNB belongs to, and thereby avoidassociating HARQ information with the wrong HARQ process. With correctHARQ information, the UE can generate the expected transmissionaccording to the NDI toggle state.

The process 80 can be applied in a non subframe bundling operation. Whenthe subframe bundling operation is configured, some of the HARQprocesses are kept activated, and the rest are suspended. The number ofactivated HARQ processes is changed during a transit from the subframeto non-subframe bundling operation. In this situation, a process isprovided for configuring the HARQ reference number when the transitoccurs, in order to prevent errors in identifying the HARQ processes.

FIG. 6 illustrates a flowchart of a process 90 according to anembodiment. The process 90 is utilized for determining the HARQprocesses which are kept activated for the subframe bundling operationfor the UE of the wireless communication system. The process 90 can becompiled into the program code 614 and includes the following steps:

Step 900: Start.

Step 902: Transit from the non-subframe bundling operation to thesubframe bundling operation.

Step 904: Receive the first uplink grant at a subframe.

Step 906: Determine an activation number according to a HARQ round triptime and a subframe bundle size.

Step 908: Generate a HARQ reference number sequence corresponding tosome of the HARQ processes for use in the subframe bundling operationaccording to the subframe, the HARQ reference number and the activationnumber.

Step 910: End.

According to the process 90, when the UE in the non-subframe bundlingoperation activates the subframe bundling operation with a subframebundle size, and receives the first uplink grant from the eNB, the UEdetermines the activation number (the number of uplink HARQ processesthat shall be kept activated) according to a HARQ round trip time andthe subframe bundle size. After that, the UE generates the HARQreference number sequence indicating the uplink HARQ processes thatshall be remained activating in the subframe bundling operation.

In addition, the uplink HARQ processes, whose HARQ reference numbers arenot indicated by the HARQ reference number sequence, are de-activatedwhen the HARQ reference number sequence is generated. Therefore, whenthe number of the HARQ processes changes during the transit from thenon-subframe to the subframe bundling operation, this embodiment allowsexplicit determination of which HARQ processes are kept activated foruplink data transmission.

With reference to FIG. 7, as an example, determination of the HARQprocesses used in the subframe bundling operation where a transmissionshall be performed four subframes after the subframe at which the UEreceives corresponding uplink grant is now described. In this example, atime length of a subframe/TTI is 1 ms (millisecond); a subframe bundlesize is set to 4, and a HARQ round trip time of the subframe bundlingoperation is 16 ms. Therefore, the activation number is determined by16/4=4. As can be seen in FIG. 7, three HRN cycles are revealed. Whenthe subframe bundling operation is configured at HRN=‘2’ of the firstHRN cycle, and the UE obtains the first uplink grant at a subframeSN=‘3’ corresponding to HRN=‘3’ of the first HRN cycle, the UE transmitsuplink data at SN=‘7’ (four subframes after the subframe SN=‘3’)corresponding to HRN=‘7’ of the first HRN cycle, and thereby the firstHARQ reference number HRN=‘7’ of the HARQ reference number sequence isobtained. Since the activation number is 4, the UE keeps four successiveHARQ reference number from HRNs ‘7’ to ‘2’. That is, the HARQ referencenumber sequence is ‘7’, ‘0’, ‘1’ and ‘2’ in HRN.

After determining the HARQ reference number sequence, the UE allocateseach of HARQ reference numbers of the HARQ reference number sequence{‘7’, ‘0’, ‘1’, ‘2’} to consecutive subframe bundles using the followingformula (F1):

{(n, n, n, . . . )_(bs), (n+1, n+1, n+1, . . . )_(bs), (n+2, n+2, n+2, .. . )_(bs), (n+3, n+3, n+3, , . . . ) bs, . . . }, wherein n is thefirst HARQ reference number of the HARQ reference number sequence, andbs is the subframe bundle size.

According to the formula (F1), the HARQ reference numbers allocated toconsecutive subframes are {(7, 7, 7, 7), (0, 0, 0, 0), (1, 1, 1, 1), (2,2, 2, 2)} in cyclic form. Therefore, the uplink HARQ processes used inthe subframe bundling operation for subframe bundle transmission areperformed based on the allocated HARQ reference numbers.

Also with reference to FIG. 7, for a transmission pattern TP1 of thesubframe bundle transmission. Since the subframe bundle size is 4, eachHARQ process shall transmit the same uplink data on four consecutivesubframes. In this situation, for the first uplink grant at HRN=‘3’ ofthe first HRN cycle, uplink data of the HARQ process with HRN=‘7’ iscontinuously transmitted on the SN−‘7’, ‘8’, ‘9’, and ‘0’. Furthermore,the UE receives the second uplink grant at the subframe HRN=‘0’ of thesecond HRN cycle. For the second uplink grant corresponding to HRN=‘0’of the second cycle, uplink data of the HARQ process with HRN=‘0’ iscontinuously transmitted on SN=‘2’, ‘3 ’, ‘4,’ and ‘5’ of the second HRNcycle.

In addition, another transmission pattern TP2 of the subframe bundletransmission is also depicted in FIG. 7. The first and second embodiedmethods differ in the transmission for the second grant. In the secondembodied method, the UE only transmits the HARQ process (HRN=‘0’) 3times on SN=‘2’, ‘3’, and ‘4’ of the second cycle since the lastsubframe of the bundle is allocated to the HARQ process with HRN=‘1’.Therefore, the HARQ process (HRN=‘1’) still can perform transmission ona complete subframe bundle if necessary.

Please note that, within the subframe bundling operation, HARQretransmissions are non-adaptive and are performed without waiting forfeedback of previous transmissions. The feedback for a bundle is onlyreceived for the subframe corresponding to the last subframe of thebundle.

In addition to the formula (F1), another way for allocating each of theHARQ reference numbers of the HARQ reference number sequence to subframebundles according to reception of uplink grants by the following formula(F2):

n, n+1, n+2, n+3, n, n+1, n+2, n+3, . . . , wherein n is the first HARQreference number of the HARQ reference number sequence, each element isused for a subframe bundle transmission.

FIG. 8 illustrates a second example based on the process 90. Since theHARQ reference number sequence with HRN=‘7’, ‘0’, ‘1’ and ‘2 isdetermined, the first HARQ reference number n=7 is obtained. Then, thefirst HRN=‘7’ is allocated to a subframe bundle corresponding to thefirst uplink grant. The second HRN=‘0’ is allocated to a subframe bundlecorresponding to the second uplink grant. Similarly, the third andfourth HRNs are allocated in the same way if the uplink grants areavailable. The HARQ reference number sequence with HRN=‘7’, ‘0’, ‘1’ and‘2 is allocated to related uplink grants in cyclic form.

In FIG. 8, the transmission related to an uplink grant occurs foursubframes after the subframe where the uplink grant is received. As canbe seen, for the first uplink grant at HRN=‘3’ of the first cycle, dataof the HARQ process with HRN=‘7’ is continuously transmitted on theSN=‘7’ (first cycle), ‘8’, ‘9’, and ‘0’. For the second uplink grant atHRN−‘0’ of the second cycle, data of the HARQ process with HRN=‘0’ iscontinuously transmitted on SN=‘2’, ‘3’, ‘4,’ and ‘5’ of the secondcycle. For the third uplink grant at HRN=‘7’ of the second cycle, dataof the HARQ process with HRN=‘1’ is continuously transmitted on SN=‘9’,‘0’, ‘1,’ and ‘2’ of the second cycle. Unlike the HARQ reference numbersequence allocation in FIG. 7, the HARQ reference number sequence isallocated to subframe bundles when an uplink grant is received;otherwise, the HARQ reference number sequence allocation for datatransmission is not performed. Therefore, when the UE performs subframebundle transmission according to the allocated HARQ reference numbersequence, there is no transmission disability of a certain HARQ process.

According to the process 90, when the UE in the non-subframe bundlingoperation activates the subframe bundling operation according to anindication from the network, the UE and the network can determine theHARQ processes for continuous activation. In this situation, the UE isable to distinguish which HARQ process corresponds to the received HARQinformation and thereby can apply accurate HARQ configuration togenerate a new transmission, or an adaptive retransmission according tothe HARQ information.

In the abovementioned embodiments, the uplink grant can be sent on aPDCCH (Physical Dedicated Control Channel) or a PHICH (Physical HybridAutomatic Repeat Request Indicator Channel) or be a Semi-PersistentScheduling grant. The transmission data of the HARQ processes can besent on for a PUSCH (Physical Uplink Shared Channel) transmission.

Moreover, the number of HARQ processes used in the non-subframe bundlingoperation changes during a transit from the subframe bundling operationto the non-subframe bundling operation. The UE needs to activate thesuspended HARQ processes and determines the initial HARQ process of thesubframe bundling operation. FIG. 9 illustrates a flowchart of a process10 according to an embodiment. The process 10 is utilized for activatingsuspended HARQ processes in the subframe bundling operation. The process10 can be compiled into the program code 614 and includes the followingsteps:

Step 100: Start.

Step 102: When a transit from the subframe bundling operation to thenon-subframe bundling operation occurs, determine a HARQ referencenumber of the first subframe of the non-subframe bundling operationaccording to a HARQ reference number of the subframe where the subframebundling operation is indicated to be deactivated.

Step 104: Allocate HARQ reference numbers to subframes of thenon-subframe bundling operation in an incremental and cyclic way with aninitial HARQ reference number of the HARQ reference number of the firstsubframe.

Step 106: End.

According to the process 10, when the UE in the subframe bundlingoperation deactivates the subframe bundling operation at a subframe, theUE determines an initial HARQ reference number according to thesubframe, and then allocates the HARQ reference numbers to followingsubframes of the non-subframe bundling operation in an incremental andcyclic way according to the initial HARQ reference number.

In FIG. 8 the UE deactivates subframe bundling operation at SN=‘2’(third cycle) corresponding to HRN=‘6’, and then transmits uplink dataat SN=‘3’. The HRN=‘6’ is the HRN of the subframe where the subframebundling operation is deactivated. With this, the UE allocates the HARQreference numbers to consecutive subframes of the non-subframe bundlingoperation by the following formula (F3):

p+1, p+2, p+3, . . . where (p+1) is the initial HARQ reference number

That is, the UE allocates the HARQ reference numbers [7, 0, 1, 2, 3, 4,5, 6] in incremental and cyclic way. The HARQ processes with HRNs=3, 4,5, 6 are re-activated. Data transmission of the HARQ processes shallbase on the allocated HARQ reference numbers of 7, 0, 1, 2, 3, 4, 5, 6.

As mentioned above, when UE in the subframe bundling operationdeactivates the subframe bundling operation, the number of the HARQprocesses for non-subframe bundling operation changes. Therefore,according to the process 10, the UE can activate the suspended HARQprocesses from the subframe bundling operation, and thereby use at most8 HARQ processes for uplink data transmission in the non-subframebundling operation.

In addition, since the subframe bundling operation is not applied to theMessage 3 of a random access procedure, Message 3 transmission possiblycollides with a subframe bundle transmission during the subframebundling operation. In this situation, the UE needs to handle thetransmission priority of Message 3 and bundle transmission to avoid atransmission error or a delay of completion of the random accessprocedure.

FIG. 10 illustrates a flowchart of a process 20 according to a fourthembodiment. The process 20 is utilized for handling Message 3transmission during collision. The process 20 can be compiled into theprogram code 614 and includes the following steps:

Step 200: Start.

Step 202: Replace a single subframe of the subframe bundle transmissionwith a transmission of the Message 3 when the transmission of theMessage 3 collides with the subframe bundle transmission at thesubframe.

Step 206: End.

According to the process 20, when the transmission of the Message 3collides with the subframe bundle transmission, the collided subframe inthe subframe bundle transmission is replaced by the Message 3transmission. Transmission contents of the subframes which do notcollide with the Message 3 are not affected by the Message 3transmission collision.

Based on the concept of the process 20, take an example of Message 3transmission collision under activation of uplink HARQ processes withHARQ reference number assignment as the examples related to FIG. 4.Please also refer to FIG. 8. During subframe bundling operation, thetransmission follows the HARQ reference number sequence HRN=‘7’, ‘0’,‘1’ and ‘2. The detail for the HARQ reference number assignment can bereferred from the above mentioned, so the detailed description isomitted herein. Thus, if the Message 3 collides with the third subframeof the bundle transmission (e.g. HRN=‘7’), in this situation, the UEtransmits the subframe bundle with the first, second, and fourthsubframes of the bundle transmission (e.g. HRN=‘7’) and uses the thirdsubframe to transmit the Message 3.

Moreover, another way for handling the Message 3 transmission when thecollision occurs is provided herein. FIG. 11 illustrates a flowchart ofa process 30 according to a fifth embodiment. The process 30 can becompiled into the program code 614 and includes the following steps:

Step 300: Start.

Step 302: When a Message 3 transmission collides with a subframe bundletransmission, prioritize the Message 3 transmission.

Step 304: End.

According to the process 30, the Message 3 has higher priority fortransmission than the bundle transmission. One way for transmitting theMessage 3 is that when the Message 3 transmission collides with thesubframe bundle transmission, the subframe bundle transmission is notcontinued. In other words, the transmission of the bundle is cancelled,and the Messages 3 are transmitted instead. Furthermore, the process 20may also be performed following the process 30.

As mentioned above, when the UE in the subframe bundling operationperforms the random access procedure, the Message 3 transmission maycollide with a bundle transmission. Therefore, the process 20 and 30 canprovide proper ways of transmitting Message 3 during collision.

Moreover, another way for handling the Message 3 to avoid a collision isto exclude transmission of the Message 3 of a random access procedurewhen a data transmission is performed according to the HARQ referencenumber sequence for the HARQ processes used in the subframe bundlingoperation. In this situation, the Message 3 transmission is applied tothe non-subframe bundling operation.

In conclusion, the embodiments assign the HARQ reference numbers to theuplink HARQ processes and the HARQ information, for the UE todistinguish which HARQ process the HARQ information received from theeNB corresponds to, and to generate an expected transmissioncorresponded to the HARQ process.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings and spirit and scope of the invention.Accordingly, the above disclosure should be construed as limited only bythe metes and bounds of the appended claims.

What is claimed is:
 1. A method of distinguishing hybrid automaticrepeat request, hereinafter called HARQ, processes for a mobile deviceof a wireless communication system, the method comprising: assigning aplurality of HARQ reference numbers corresponding to a plurality ofuplink HARQ processes respectively, for identifying each of theplurality of uplink HARQ processes; and generating each of the pluralityof HARQ reference numbers according to a subframe number ofcorresponding subframe and a HARQ round trip time.
 2. The method ofclaim 1, wherein generating each of the plurality of HARQ referencenumbers according to corresponding subframe number and the HARQ roundtrip time comprises: generating each of the plurality of HARQ referencenumbers associated to corresponding subframe by an equation:m=(subframe counter) mod HARQ round trip time, where m is a HARQreference number, the subframe counter is an integer and is incrementedby one every subframe with a predetermined cycle, and mod is a modulusoperation.
 3. The method of claim 2, wherein the subframe counter isobtained by (10* SFN +subframe number +k), where SFN indicates systemframe number, and k is 0 or an integer.
 4. The method of claim 1 furthercomprising: receiving an uplink grant; and determining a New DataIndicator (NDI) toggle state for each of the plurality of HARQ processesaccording to a first NDI value in HARQ information associated to each ofthe plurality of HARQ processes and a second NDI value in the receiveduplink grant.
 5. The method of claim 1, wherein the plurality of uplinkHARQ processes are capable of a subframe bundling operation and anon-subframe bundling operation.
 6. The method of claim 5, wherein theplurality of uplink HARQ processes operates in the non-subframe bundlingoperation, and the plurality of HARQ reference numbers are cyclicallyallocated to a plurality of subframes.
 7. The method of claim 6 furthercomprising generating each of the plurality of HARQ reference numbersassociated to corresponding subframe by an equation:m−(subframe counter) mod HARQ round trip time, where m is a HARQreference number, the subframe counter is an integer and is incrementedby one every subframe with a predetermined cycle, and mod is an moduleoperation.
 8. The method of claim 7, wherein the subframe counter isobtained by (10* SFN +subframe number +k), where SFN indicates systemframe number, and k is 0 or an integer.
 9. The method of claim 5 furthercomprising: transiting from the non-subframe bundling operation to thesubframe bundling operation; receiving a first uplink grant at a firstsubframe; determining an activation number according to a HARQ roundtrip time and a subframe bundle size; generating a HARQ reference numbersequence corresponding to some of the plurality of HARQ processes foruse in the subframe bundling operation according to the first subframe,the HARQ reference number and the activation number.
 10. The method ofclaim 9 further comprises: allocating each of HARQ reference numbers ofthe HARQ reference number sequence to a subframe bundle, wherein thesubframe bundles are consecutive.
 11. The method of claim 10 furthercomprises: performing HARQ transmission according to correspondingallocated HARQ reference numbers at the subframe bundles, excluding HARQtransmission of a Message 3 of a random access procedure.
 12. The methodof claim 10, wherein the first HARQ reference number of the HARQreference number sequence is a HARQ reference number four subframesafter the first subframe.
 13. The method of claim 9 further comprising:allocating the first HARQ reference number of the HARQ reference numbersequence to a first subframe bundle corresponding to the first uplinkgrant; receiving a second uplink grant next to the first uplink grant ata second subframe; and allocating the second HARQ reference number ofthe HARQ reference number sequence to a second subframe bundlecorresponding to the second uplink grant.
 14. The method of claim 13further comprises: performing HARQ transmission according tocorresponding allocated HARQ reference numbers at the subframe bundles,excluding HARQ transmission of a Message 3 of a random access procedure.15. The method of claim 13, wherein the first subframe bundle is foursubframes after the first subframe, and the second subframe bundle isfour subframes after the second subframe.
 16. The method of claim 9further comprising excluding transmission of a Message 3 of a randomaccess procedure when performing data transmission according to the HARQreference number sequence for the HARQ processes used in the subframebundling operation.
 17. The method of claim 16 further comprisingapplying the non-subframe bundling operation to the Message 3transmission of the random access procedure.
 18. The method of claim 5further comprising: when a transit from the subframe bundling operationto the non-subframe bundling operation occurs, determining a HARQreference number of the first subframe of the non-subframe bundlingoperation according to a HARQ reference number of the subframe where thesubframe bundling operation is indicated to be deactivated; andallocating HARQ reference numbers to subframes of the non-subframebundling operation in an incremental and cyclic way with an initial HARQreference number of the HARQ reference number of the first subframe. 19.The method of claim 5 further comprising setting a priority of a Message3 transmission higher than a priority of a subframe bundle transmission.20. The method of claim 5 further comprising replacing a subframe bundletransmission corresponding to a subframe with a transmission of theMessage 3 when the transmission of the Message 3 collides with thesubframe bundle transmission at the subframe.
 21. A method ofdistinguishing hybrid automatic repeat request, hereinafter called HARQ,processes for a mobile device of a wireless communication system, themethod comprising: respectively assigning a plurality of HARQ referencenumbers corresponding to a plurality of subframes, which correspond to aplurality of uplink HARQ processes under subframe bundling ornon-subframe bundling operation, for identifying each of the pluralityof uplink HARQ processes and the plurality of subframes; replacing asubframe bundle transmission corresponding to a subframe with atransmission of the Message 3 according to a HARQ reference numberassigned to the subframe when the transmission of the Message 3 collideswith the subframe bundle transmission at the subframe.
 22. The method ofclaim 21 further comprising applying the non-subframe bundling operationto the Message 3 transmission of the random access procedure.
 23. Amethod of distinguishing hybrid automatic repeat request, hereinaftercalled HARQ, processes for a mobile device of a wireless communicationsystem, the method comprising: prioritizing a transmission of Message 3higher than a subframe bundle transmission; replacing a single subframeof the subframe bundle transmission with the transmission of the Message3 when the transmission of the Message 3 collides with the subframebundle transmission at the subframe; and applying a non-subframebundling operation to the transmission of the Message 3 of an randomaccess procedure.
 24. The method of claim 23 further comprises:discontinuing the subframe bundle transmission when the transmission ofthe Message 3 collides with any single subframe of the subframe bundletransmission.
 25. A method of distinguishing hybrid automatic repeatrequest, hereinafter called HARQ, processes for a mobile device of awireless communication system, the method comprising: prioritizing atransmission of Message 3 higher than a subframe bundle transmission;discontinuing the subframe bundle transmission when the transmission ofthe Message 3 collides with any single subframe of the subframe bundletransmission; and applying a non-subframe bundling operation to thetransmission of the Message 3 of an random access procedure.